Our objective is to develop an organoid in vitro model of liver cell carcinogenesis which will utilize oncodevelopmental liver enzymes as markers of cell type and function, initially to identify the cell population at risk and subsequently to establish an index of neoplastic transformation. To do this, we will use a new method for culturing liver cells on the epidermal surface of sterile dead pigskin. These cultures will be exposed to chemical carcinogens. Before, during and after transformation, the cultures will be examined for oncodevelopmental enzyme patterns. Ontogeny as it occurs and is altered by chemical carcinogens in vitro will be compared to normal ontogeny in vivo.